MT
Mervyn Thomas
Tue, Aug 30, 2022 12:53 AM
Stephen,
An idea I may try -thanks for your response. The current involved in
the EFC line to the oscillator is extremely small-button cells would
last years.
Merv
On 29/08/2022 8:42 pm, Stephen C. Menasian via time-nuts wrote:
Merv,
If I understand your problem, the 10811's VCO control input voltage has
drifted above the output range of the GPSD driver board. If the VCO
control terminal current is low enough, you might be able to quickly solve
this problem by putting 1 or 2 Lithium Ion Coin cells in series with the
control lead. If only a few microamperes are involved, this solutin might
last several years.
Stephen Menasian
On Mon, 29 Aug 2022 15:56:52 +0800
Mervyn Thomas via time-nuts time-nuts@lists.febo.com wrote:
Hi Bill,
Unfortunately the 2 HP 10811's I have have no way to poke anything thru
the can to adjust a capacitor. They are completely enclosed in an
aluminium can with 2 power leads coming out with 6 pin female
connectors on the end which go to the power board as used in the HP
Z3801 GPSDO and 2 thin coax cables with SMB connectors - one marked as
10 MHz and the other as EFC. I may have to replace mine with the model
that has the tuning capacitor.
Thanks for your response.
73 Merv
On 29/08/2022 12:45 pm, Bill Beam via time-nuts wrote:
I also run a Brooks Shera/HP 10811. Still going after many years.
You must live with the limited steering voltage.
The solution is to adjust the HP 10811 tuning capacitor to get it
back near a frequency that the EFC can handle.
I have had to do this more than once. Also if replacing the
oscillator its tuning capacitor may need adjustment.
On Mon, 29 Aug 2022 11:25:26 +0800, Mervyn Thomas via time-nuts wrote:
Hi All,
I'm new to time nuts but here goes.
I built a GPS disciplined- 10MHz osc about 15 + years ago.- It
uses an HP 10811 D/Oven Oscillator and the Brooks Shera PCB and
software V402N.- The physical construction article was per James
Miller G3RUH. This unit has worked flawlessly for all these years
but now is unable to hold the freq to precisely 10MHz - it is
constantly .29 to.60 Hz high.- The DAC output which controls the EFC
into the osc outputs a negative only adjustable voltage between -3v
down to 0V and is settable by varying a 10K potentiometer.- The
Osc. now needs abouit +0.46V to bring it down to 10MHz but the DAC
does not seem able to output a positive voltage.- The DAC is an
AD1861 (obsolete) and has a +5V applied to pin 16 and a -5V applied
to pins 1 and 8. My first reaction was the HP osc. had reached the
end of it's life but the datasheet states the EFC control voltage
can be between a plus 5V and a minus 5V which varies the freq by 1Hz
so it seems it is just over half way through it's life.
I feel the Brooks s/ware would have provided some method to ensure
the DAC output could be adjusted to swing the full full 5V or at
least 3V?- I have the source code but I'm no programmer so would
appreciate any help someone can provide please.
73 de Merv- VK6BMT
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
Bill Beam
NL7F
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Stephen,
An idea I may try -thanks for your response. The current involved in
the EFC line to the oscillator is extremely small-button cells would
last years.
Merv
On 29/08/2022 8:42 pm, Stephen C. Menasian via time-nuts wrote:
> Merv,
>
> If I understand your problem, the 10811's VCO control input voltage has
> drifted above the output range of the GPSD driver board. If the VCO
> control terminal current is low enough, you might be able to quickly solve
> this problem by putting 1 or 2 Lithium Ion Coin cells in series with the
> control lead. If only a few microamperes are involved, this solutin might
> last several years.
>
> Stephen Menasian
>
> On Mon, 29 Aug 2022 15:56:52 +0800
> Mervyn Thomas via time-nuts <time-nuts@lists.febo.com> wrote:
>
>> Hi Bill,
>>
>> Unfortunately the 2 HP 10811's I have have no way to poke anything thru
>> the can to adjust a capacitor. They are completely enclosed in an
>> aluminium can with 2 power leads coming out with 6 pin female
>> connectors on the end which go to the power board as used in the HP
>> Z3801 GPSDO and 2 thin coax cables with SMB connectors - one marked as
>> 10 MHz and the other as EFC. I may have to replace mine with the model
>> that has the tuning capacitor.
>>
>> Thanks for your response.
>>
>> 73 Merv
>>
>> On 29/08/2022 12:45 pm, Bill Beam via time-nuts wrote:
>>> I also run a Brooks Shera/HP 10811. Still going after many years.
>>> You must live with the limited steering voltage.
>>> The solution is to adjust the HP 10811 tuning capacitor to get it
>>> back near a frequency that the EFC can handle.
>>> I have had to do this more than once. Also if replacing the
>>> oscillator its tuning capacitor may need adjustment.
>>>
>>> On Mon, 29 Aug 2022 11:25:26 +0800, Mervyn Thomas via time-nuts wrote:
>>>
>>>> Hi All,
>>>> I'm new to time nuts but here goes.
>>>> I built a GPS disciplined- 10MHz osc about 15 + years ago.- It
>>>> uses an HP 10811 D/Oven Oscillator and the Brooks Shera PCB and
>>>> software V402N.- The physical construction article was per James
>>>> Miller G3RUH. This unit has worked flawlessly for all these years
>>>> but now is unable to hold the freq to precisely 10MHz - it is
>>>> constantly .29 to.60 Hz high.- The DAC output which controls the EFC
>>>> into the osc outputs a negative only adjustable voltage between -3v
>>>> down to 0V and is settable by varying a 10K potentiometer.- The
>>>> Osc. now needs abouit +0.46V to bring it down to 10MHz but the DAC
>>>> does not seem able to output a positive voltage.- The DAC is an
>>>> AD1861 (obsolete) and has a +5V applied to pin 16 and a -5V applied
>>>> to pins 1 and 8. My first reaction was the HP osc. had reached the
>>>> end of it's life but the datasheet states the EFC control voltage
>>>> can be between a plus 5V and a minus 5V which varies the freq by 1Hz
>>>> so it seems it is just over half way through it's life.
>>>> I feel the Brooks s/ware would have provided some method to ensure
>>>> the DAC output could be adjusted to swing the full full 5V or at
>>>> least 3V?- I have the source code but I'm no programmer so would
>>>> appreciate any help someone can provide please.
>>>> 73 de Merv- VK6BMT
>>>> _______________________________________________
>>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>>> Bill Beam
>>> NL7F
>>>
>>>
>>>
>>> _______________________________________________
>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>> _______________________________________________
>> time-nuts mailing list -- time-nuts@lists.febo.com
>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
> _______________________________________________
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe send an email to time-nuts-leave@lists.febo.com
PS
paul swed
Tue, Aug 30, 2022 1:39 PM
Pretty clever approach to establishing an offset. But doesn't it matter how
the vari-cap is hooked up in the oscillator circuit? If the veri-cap needs
a negative voltage to work that may indicate the cathode is at ground and
the positive voltage would forward bias the vari-cap. Just thinking about
the possible impact.
Though the cost of experimenting is $0. No harm.
Regards
Paul
WB8TSL
On Tue, Aug 30, 2022 at 1:22 AM Mervyn Thomas via time-nuts <
time-nuts@lists.febo.com> wrote:
Stephen,
An idea I may try -thanks for your response. The current involved in
the EFC line to the oscillator is extremely small-button cells would
last years.
Merv
On 29/08/2022 8:42 pm, Stephen C. Menasian via time-nuts wrote:
Merv,
If I understand your problem, the 10811's VCO control input voltage has
drifted above the output range of the GPSD driver board. If the VCO
control terminal current is low enough, you might be able to quickly
this problem by putting 1 or 2 Lithium Ion Coin cells in series with the
control lead. If only a few microamperes are involved, this solutin might
last several years.
Stephen Menasian
On Mon, 29 Aug 2022 15:56:52 +0800
Mervyn Thomas via time-nuts time-nuts@lists.febo.com wrote:
Hi Bill,
Unfortunately the 2 HP 10811's I have have no way to poke anything thru
the can to adjust a capacitor. They are completely enclosed in an
aluminium can with 2 power leads coming out with 6 pin female
connectors on the end which go to the power board as used in the HP
Z3801 GPSDO and 2 thin coax cables with SMB connectors - one marked as
10 MHz and the other as EFC. I may have to replace mine with the model
that has the tuning capacitor.
Thanks for your response.
73 Merv
On 29/08/2022 12:45 pm, Bill Beam via time-nuts wrote:
I also run a Brooks Shera/HP 10811. Still going after many years.
You must live with the limited steering voltage.
The solution is to adjust the HP 10811 tuning capacitor to get it
back near a frequency that the EFC can handle.
I have had to do this more than once. Also if replacing the
oscillator its tuning capacitor may need adjustment.
On Mon, 29 Aug 2022 11:25:26 +0800, Mervyn Thomas via time-nuts wrote:
Hi All,
I'm new to time nuts but here goes.
I built a GPS disciplined- 10MHz osc about 15 + years ago.- It
uses an HP 10811 D/Oven Oscillator and the Brooks Shera PCB and
software V402N.- The physical construction article was per James
Miller G3RUH. This unit has worked flawlessly for all these years
but now is unable to hold the freq to precisely 10MHz - it is
constantly .29 to.60 Hz high.- The DAC output which controls the EFC
into the osc outputs a negative only adjustable voltage between -3v
down to 0V and is settable by varying a 10K potentiometer.- The
Osc. now needs abouit +0.46V to bring it down to 10MHz but the DAC
does not seem able to output a positive voltage.- The DAC is an
AD1861 (obsolete) and has a +5V applied to pin 16 and a -5V applied
to pins 1 and 8. My first reaction was the HP osc. had reached the
end of it's life but the datasheet states the EFC control voltage
can be between a plus 5V and a minus 5V which varies the freq by 1Hz
so it seems it is just over half way through it's life.
I feel the Brooks s/ware would have provided some method to ensure
the DAC output could be adjusted to swing the full full 5V or at
least 3V?- I have the source code but I'm no programmer so would
appreciate any help someone can provide please.
73 de Merv- VK6BMT
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
Pretty clever approach to establishing an offset. But doesn't it matter how
the vari-cap is hooked up in the oscillator circuit? If the veri-cap needs
a negative voltage to work that may indicate the cathode is at ground and
the positive voltage would forward bias the vari-cap. Just thinking about
the possible impact.
Though the cost of experimenting is $0. No harm.
Regards
Paul
WB8TSL
On Tue, Aug 30, 2022 at 1:22 AM Mervyn Thomas via time-nuts <
time-nuts@lists.febo.com> wrote:
> Stephen,
>
> An idea I may try -thanks for your response. The current involved in
> the EFC line to the oscillator is extremely small-button cells would
> last years.
>
> Merv
>
> On 29/08/2022 8:42 pm, Stephen C. Menasian via time-nuts wrote:
> > Merv,
> >
> > If I understand your problem, the 10811's VCO control input voltage has
> > drifted above the output range of the GPSD driver board. If the VCO
> > control terminal current is low enough, you might be able to quickly
> solve
> > this problem by putting 1 or 2 Lithium Ion Coin cells in series with the
> > control lead. If only a few microamperes are involved, this solutin might
> > last several years.
> >
> > Stephen Menasian
> >
> > On Mon, 29 Aug 2022 15:56:52 +0800
> > Mervyn Thomas via time-nuts <time-nuts@lists.febo.com> wrote:
> >
> >> Hi Bill,
> >>
> >> Unfortunately the 2 HP 10811's I have have no way to poke anything thru
> >> the can to adjust a capacitor. They are completely enclosed in an
> >> aluminium can with 2 power leads coming out with 6 pin female
> >> connectors on the end which go to the power board as used in the HP
> >> Z3801 GPSDO and 2 thin coax cables with SMB connectors - one marked as
> >> 10 MHz and the other as EFC. I may have to replace mine with the model
> >> that has the tuning capacitor.
> >>
> >> Thanks for your response.
> >>
> >> 73 Merv
> >>
> >> On 29/08/2022 12:45 pm, Bill Beam via time-nuts wrote:
> >>> I also run a Brooks Shera/HP 10811. Still going after many years.
> >>> You must live with the limited steering voltage.
> >>> The solution is to adjust the HP 10811 tuning capacitor to get it
> >>> back near a frequency that the EFC can handle.
> >>> I have had to do this more than once. Also if replacing the
> >>> oscillator its tuning capacitor may need adjustment.
> >>>
> >>> On Mon, 29 Aug 2022 11:25:26 +0800, Mervyn Thomas via time-nuts wrote:
> >>>
> >>>> Hi All,
> >>>> I'm new to time nuts but here goes.
> >>>> I built a GPS disciplined- 10MHz osc about 15 + years ago.- It
> >>>> uses an HP 10811 D/Oven Oscillator and the Brooks Shera PCB and
> >>>> software V402N.- The physical construction article was per James
> >>>> Miller G3RUH. This unit has worked flawlessly for all these years
> >>>> but now is unable to hold the freq to precisely 10MHz - it is
> >>>> constantly .29 to.60 Hz high.- The DAC output which controls the EFC
> >>>> into the osc outputs a negative only adjustable voltage between -3v
> >>>> down to 0V and is settable by varying a 10K potentiometer.- The
> >>>> Osc. now needs abouit +0.46V to bring it down to 10MHz but the DAC
> >>>> does not seem able to output a positive voltage.- The DAC is an
> >>>> AD1861 (obsolete) and has a +5V applied to pin 16 and a -5V applied
> >>>> to pins 1 and 8. My first reaction was the HP osc. had reached the
> >>>> end of it's life but the datasheet states the EFC control voltage
> >>>> can be between a plus 5V and a minus 5V which varies the freq by 1Hz
> >>>> so it seems it is just over half way through it's life.
> >>>> I feel the Brooks s/ware would have provided some method to ensure
> >>>> the DAC output could be adjusted to swing the full full 5V or at
> >>>> least 3V?- I have the source code but I'm no programmer so would
> >>>> appreciate any help someone can provide please.
> >>>> 73 de Merv- VK6BMT
> >>>> _______________________________________________
> >>>> time-nuts mailing list -- time-nuts@lists.febo.com
> >>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
> >>> Bill Beam
> >>> NL7F
> >>>
> >>>
> >>>
> >>> _______________________________________________
> >>> time-nuts mailing list -- time-nuts@lists.febo.com
> >>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
> >> _______________________________________________
> >> time-nuts mailing list -- time-nuts@lists.febo.com
> >> To unsubscribe send an email to time-nuts-leave@lists.febo.com
> > _______________________________________________
> > time-nuts mailing list -- time-nuts@lists.febo.com
> > To unsubscribe send an email to time-nuts-leave@lists.febo.com
> _______________________________________________
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe send an email to time-nuts-leave@lists.febo.com
SC
Stephen C. Menasian
Tue, Aug 30, 2022 2:27 PM
Paul,
That is a valid consideration. Unfortunately, I don't have a schematic of
the oscillator and can't say, definitely, whether is relevant. In trying
this out, I would start with an adjustable DC power supply with a
microammeter in series with its output and monitor the current as the
voltage is increased from zero. This would be necessary, anyway, to
estimate the expected cell life. A current rise resembling a a diode
turn-on knee would serve to establish the limit. I wouldn't ever let it
rise above 1 mA or so. Some varactors have MAX forward currents in the
10s of mA range. If the knee is found at a voltage below the Li ion
coin cell range, a 1.5 Volt cell might be in order. Also, I would monitor
the oscillator output frequency as I did this. After all, if one can't
reach 10 MHz without forward biasing the varactor, the only course of
action might be to cut the oscillator can open.
Something occurred to me. Does the oscillator have a glued-on label?
Sometimes these are used to cover access holes to "factory-only"
adjustments. One can often locate this type of hole with ones finger
by pressing on the label and feeling for a depression.
Stephen
On Tue, 30 Aug 2022 09:39:36 -0400
paul swed via time-nuts time-nuts@lists.febo.com wrote:
Pretty clever approach to establishing an offset. But doesn't it matter
how the vari-cap is hooked up in the oscillator circuit? If the
veri-cap needs a negative voltage to work that may indicate the cathode
is at ground and the positive voltage would forward bias the vari-cap.
Just thinking about the possible impact.
Though the cost of experimenting is $0. No harm.
Regards
Paul
WB8TSL
On Tue, Aug 30, 2022 at 1:22 AM Mervyn Thomas via time-nuts <
time-nuts@lists.febo.com> wrote:
Stephen,
An idea I may try -thanks for your response. The current involved in
the EFC line to the oscillator is extremely small-button cells would
last years.
Merv
On 29/08/2022 8:42 pm, Stephen C. Menasian via time-nuts wrote:
Merv,
If I understand your problem, the 10811's VCO control input voltage
has drifted above the output range of the GPSD driver board. If the
VCO control terminal current is low enough, you might be able to
quickly
solve
this problem by putting 1 or 2 Lithium Ion Coin cells in series
with the control lead. If only a few microamperes are involved,
this solutin might last several years.
Stephen Menasian
On Mon, 29 Aug 2022 15:56:52 +0800
Mervyn Thomas via time-nuts time-nuts@lists.febo.com wrote:
Hi Bill,
Unfortunately the 2 HP 10811's I have have no way to poke anything
thru the can to adjust a capacitor. They are completely enclosed
in an aluminium can with 2 power leads coming out with 6 pin female
connectors on the end which go to the power board as used in the HP
Z3801 GPSDO and 2 thin coax cables with SMB connectors - one
marked as 10 MHz and the other as EFC. I may have to replace mine
with the model that has the tuning capacitor.
Thanks for your response.
73 Merv
On 29/08/2022 12:45 pm, Bill Beam via time-nuts wrote:
I also run a Brooks Shera/HP 10811. Still going after many years.
You must live with the limited steering voltage.
The solution is to adjust the HP 10811 tuning capacitor to get it
back near a frequency that the EFC can handle.
I have had to do this more than once. Also if replacing the
oscillator its tuning capacitor may need adjustment.
On Mon, 29 Aug 2022 11:25:26 +0800, Mervyn Thomas via time-nuts
wrote:
Hi All,
I'm new to time nuts but here goes.
I built a GPS disciplined- 10MHz osc about 15 + years ago.- It
uses an HP 10811 D/Oven Oscillator and the Brooks Shera PCB and
software V402N.- The physical construction article was per James
Miller G3RUH. This unit has worked flawlessly for all these years
but now is unable to hold the freq to precisely 10MHz - it is
constantly .29 to.60 Hz high.- The DAC output which controls the
EFC into the osc outputs a negative only adjustable voltage
between -3v down to 0V and is settable by varying a 10K
potentiometer.- The Osc. now needs abouit +0.46V to bring it
down to 10MHz but the DAC does not seem able to output a
positive voltage.- The DAC is an AD1861 (obsolete) and has a
+5V applied to pin 16 and a -5V applied to pins 1 and 8. My
first reaction was the HP osc. had reached the end of it's life
but the datasheet states the EFC control voltage can be between
a plus 5V and a minus 5V which varies the freq by 1Hz so it
seems it is just over half way through it's life. I feel the
Brooks s/ware would have provided some method to ensure the DAC
output could be adjusted to swing the full full 5V or at least
3V?- I have the source code but I'm no programmer so would
appreciate any help someone can provide please. 73 de Merv-
VK6BMT _______________________________________________
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
Bill Beam
NL7F
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
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To unsubscribe send an email to time-nuts-leave@lists.febo.com
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To unsubscribe send an email to time-nuts-leave@lists.febo.com
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To unsubscribe send an email to time-nuts-leave@lists.febo.com
Paul,
That is a valid consideration. Unfortunately, I don't have a schematic of
the oscillator and can't say, definitely, whether is relevant. In trying
this out, I would start with an adjustable DC power supply with a
microammeter in series with its output and monitor the current as the
voltage is increased from zero. This would be necessary, anyway, to
estimate the expected cell life. A current rise resembling a a diode
turn-on knee would serve to establish the limit. I wouldn't ever let it
rise above 1 mA or so. Some varactors have MAX forward currents in the
10s of mA range. If the knee is found at a voltage below the Li ion
coin cell range, a 1.5 Volt cell might be in order. Also, I would monitor
the oscillator output frequency as I did this. After all, if one can't
reach 10 MHz without forward biasing the varactor, the only course of
action might be to cut the oscillator can open.
Something occurred to me. Does the oscillator have a glued-on label?
Sometimes these are used to cover access holes to "factory-only"
adjustments. One can often locate this type of hole with ones finger
by pressing on the label and feeling for a depression.
Stephen
On Tue, 30 Aug 2022 09:39:36 -0400
paul swed via time-nuts <time-nuts@lists.febo.com> wrote:
> Pretty clever approach to establishing an offset. But doesn't it matter
> how the vari-cap is hooked up in the oscillator circuit? If the
> veri-cap needs a negative voltage to work that may indicate the cathode
> is at ground and the positive voltage would forward bias the vari-cap.
> Just thinking about the possible impact.
> Though the cost of experimenting is $0. No harm.
> Regards
> Paul
> WB8TSL
>
> On Tue, Aug 30, 2022 at 1:22 AM Mervyn Thomas via time-nuts <
> time-nuts@lists.febo.com> wrote:
>
> > Stephen,
> >
> > An idea I may try -thanks for your response. The current involved in
> > the EFC line to the oscillator is extremely small-button cells would
> > last years.
> >
> > Merv
> >
> > On 29/08/2022 8:42 pm, Stephen C. Menasian via time-nuts wrote:
> > > Merv,
> > >
> > > If I understand your problem, the 10811's VCO control input voltage
> > > has drifted above the output range of the GPSD driver board. If the
> > > VCO control terminal current is low enough, you might be able to
> > > quickly
> > solve
> > > this problem by putting 1 or 2 Lithium Ion Coin cells in series
> > > with the control lead. If only a few microamperes are involved,
> > > this solutin might last several years.
> > >
> > > Stephen Menasian
> > >
> > > On Mon, 29 Aug 2022 15:56:52 +0800
> > > Mervyn Thomas via time-nuts <time-nuts@lists.febo.com> wrote:
> > >
> > >> Hi Bill,
> > >>
> > >> Unfortunately the 2 HP 10811's I have have no way to poke anything
> > >> thru the can to adjust a capacitor. They are completely enclosed
> > >> in an aluminium can with 2 power leads coming out with 6 pin female
> > >> connectors on the end which go to the power board as used in the HP
> > >> Z3801 GPSDO and 2 thin coax cables with SMB connectors - one
> > >> marked as 10 MHz and the other as EFC. I may have to replace mine
> > >> with the model that has the tuning capacitor.
> > >>
> > >> Thanks for your response.
> > >>
> > >> 73 Merv
> > >>
> > >> On 29/08/2022 12:45 pm, Bill Beam via time-nuts wrote:
> > >>> I also run a Brooks Shera/HP 10811. Still going after many years.
> > >>> You must live with the limited steering voltage.
> > >>> The solution is to adjust the HP 10811 tuning capacitor to get it
> > >>> back near a frequency that the EFC can handle.
> > >>> I have had to do this more than once. Also if replacing the
> > >>> oscillator its tuning capacitor may need adjustment.
> > >>>
> > >>> On Mon, 29 Aug 2022 11:25:26 +0800, Mervyn Thomas via time-nuts
> > >>> wrote:
> > >>>> Hi All,
> > >>>> I'm new to time nuts but here goes.
> > >>>> I built a GPS disciplined- 10MHz osc about 15 + years ago.- It
> > >>>> uses an HP 10811 D/Oven Oscillator and the Brooks Shera PCB and
> > >>>> software V402N.- The physical construction article was per James
> > >>>> Miller G3RUH. This unit has worked flawlessly for all these years
> > >>>> but now is unable to hold the freq to precisely 10MHz - it is
> > >>>> constantly .29 to.60 Hz high.- The DAC output which controls the
> > >>>> EFC into the osc outputs a negative only adjustable voltage
> > >>>> between -3v down to 0V and is settable by varying a 10K
> > >>>> potentiometer.- The Osc. now needs abouit +0.46V to bring it
> > >>>> down to 10MHz but the DAC does not seem able to output a
> > >>>> positive voltage.- The DAC is an AD1861 (obsolete) and has a
> > >>>> +5V applied to pin 16 and a -5V applied to pins 1 and 8. My
> > >>>> first reaction was the HP osc. had reached the end of it's life
> > >>>> but the datasheet states the EFC control voltage can be between
> > >>>> a plus 5V and a minus 5V which varies the freq by 1Hz so it
> > >>>> seems it is just over half way through it's life. I feel the
> > >>>> Brooks s/ware would have provided some method to ensure the DAC
> > >>>> output could be adjusted to swing the full full 5V or at least
> > >>>> 3V?- I have the source code but I'm no programmer so would
> > >>>> appreciate any help someone can provide please. 73 de Merv-
> > >>>> VK6BMT _______________________________________________
> > >>>> time-nuts mailing list -- time-nuts@lists.febo.com
> > >>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
> > >>> Bill Beam
> > >>> NL7F
> > >>>
> > >>>
> > >>>
> > >>> _______________________________________________
> > >>> time-nuts mailing list -- time-nuts@lists.febo.com
> > >>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
> > >> _______________________________________________
> > >> time-nuts mailing list -- time-nuts@lists.febo.com
> > >> To unsubscribe send an email to time-nuts-leave@lists.febo.com
> > > _______________________________________________
> > > time-nuts mailing list -- time-nuts@lists.febo.com
> > > To unsubscribe send an email to time-nuts-leave@lists.febo.com
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> > time-nuts mailing list -- time-nuts@lists.febo.com
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>
BK
Bob kb8tq
Tue, Aug 30, 2022 6:59 PM
Hi
If you check the 10811 schematic, the varicap is biased at roughly +6.8V internally.
The other side of the diode is what the EFC is driving. This gives them the +/- 5V
range they specify on the 10811 data sheet.
Bob
On Aug 30, 2022, at 5:39 AM, paul swed via time-nuts time-nuts@lists.febo.com wrote:
Pretty clever approach to establishing an offset. But doesn't it matter how
the vari-cap is hooked up in the oscillator circuit? If the veri-cap needs
a negative voltage to work that may indicate the cathode is at ground and
the positive voltage would forward bias the vari-cap. Just thinking about
the possible impact.
Though the cost of experimenting is $0. No harm.
Regards
Paul
WB8TSL
On Tue, Aug 30, 2022 at 1:22 AM Mervyn Thomas via time-nuts <
time-nuts@lists.febo.com> wrote:
Stephen,
An idea I may try -thanks for your response. The current involved in
the EFC line to the oscillator is extremely small-button cells would
last years.
Merv
On 29/08/2022 8:42 pm, Stephen C. Menasian via time-nuts wrote:
Merv,
If I understand your problem, the 10811's VCO control input voltage has
drifted above the output range of the GPSD driver board. If the VCO
control terminal current is low enough, you might be able to quickly
this problem by putting 1 or 2 Lithium Ion Coin cells in series with the
control lead. If only a few microamperes are involved, this solutin might
last several years.
Stephen Menasian
On Mon, 29 Aug 2022 15:56:52 +0800
Mervyn Thomas via time-nuts time-nuts@lists.febo.com wrote:
Hi Bill,
Unfortunately the 2 HP 10811's I have have no way to poke anything thru
the can to adjust a capacitor. They are completely enclosed in an
aluminium can with 2 power leads coming out with 6 pin female
connectors on the end which go to the power board as used in the HP
Z3801 GPSDO and 2 thin coax cables with SMB connectors - one marked as
10 MHz and the other as EFC. I may have to replace mine with the model
that has the tuning capacitor.
Thanks for your response.
73 Merv
On 29/08/2022 12:45 pm, Bill Beam via time-nuts wrote:
I also run a Brooks Shera/HP 10811. Still going after many years.
You must live with the limited steering voltage.
The solution is to adjust the HP 10811 tuning capacitor to get it
back near a frequency that the EFC can handle.
I have had to do this more than once. Also if replacing the
oscillator its tuning capacitor may need adjustment.
On Mon, 29 Aug 2022 11:25:26 +0800, Mervyn Thomas via time-nuts wrote:
Hi All,
I'm new to time nuts but here goes.
I built a GPS disciplined- 10MHz osc about 15 + years ago.- It
uses an HP 10811 D/Oven Oscillator and the Brooks Shera PCB and
software V402N.- The physical construction article was per James
Miller G3RUH. This unit has worked flawlessly for all these years
but now is unable to hold the freq to precisely 10MHz - it is
constantly .29 to.60 Hz high.- The DAC output which controls the EFC
into the osc outputs a negative only adjustable voltage between -3v
down to 0V and is settable by varying a 10K potentiometer.- The
Osc. now needs abouit +0.46V to bring it down to 10MHz but the DAC
does not seem able to output a positive voltage.- The DAC is an
AD1861 (obsolete) and has a +5V applied to pin 16 and a -5V applied
to pins 1 and 8. My first reaction was the HP osc. had reached the
end of it's life but the datasheet states the EFC control voltage
can be between a plus 5V and a minus 5V which varies the freq by 1Hz
so it seems it is just over half way through it's life.
I feel the Brooks s/ware would have provided some method to ensure
the DAC output could be adjusted to swing the full full 5V or at
least 3V?- I have the source code but I'm no programmer so would
appreciate any help someone can provide please.
73 de Merv- VK6BMT
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
Hi
If you check the 10811 schematic, the varicap is biased at roughly +6.8V internally.
The other side of the diode is what the EFC is driving. This gives them the +/- 5V
range they specify on the 10811 data sheet.
Bob
> On Aug 30, 2022, at 5:39 AM, paul swed via time-nuts <time-nuts@lists.febo.com> wrote:
>
> Pretty clever approach to establishing an offset. But doesn't it matter how
> the vari-cap is hooked up in the oscillator circuit? If the veri-cap needs
> a negative voltage to work that may indicate the cathode is at ground and
> the positive voltage would forward bias the vari-cap. Just thinking about
> the possible impact.
> Though the cost of experimenting is $0. No harm.
> Regards
> Paul
> WB8TSL
>
> On Tue, Aug 30, 2022 at 1:22 AM Mervyn Thomas via time-nuts <
> time-nuts@lists.febo.com> wrote:
>
>> Stephen,
>>
>> An idea I may try -thanks for your response. The current involved in
>> the EFC line to the oscillator is extremely small-button cells would
>> last years.
>>
>> Merv
>>
>> On 29/08/2022 8:42 pm, Stephen C. Menasian via time-nuts wrote:
>>> Merv,
>>>
>>> If I understand your problem, the 10811's VCO control input voltage has
>>> drifted above the output range of the GPSD driver board. If the VCO
>>> control terminal current is low enough, you might be able to quickly
>> solve
>>> this problem by putting 1 or 2 Lithium Ion Coin cells in series with the
>>> control lead. If only a few microamperes are involved, this solutin might
>>> last several years.
>>>
>>> Stephen Menasian
>>>
>>> On Mon, 29 Aug 2022 15:56:52 +0800
>>> Mervyn Thomas via time-nuts <time-nuts@lists.febo.com> wrote:
>>>
>>>> Hi Bill,
>>>>
>>>> Unfortunately the 2 HP 10811's I have have no way to poke anything thru
>>>> the can to adjust a capacitor. They are completely enclosed in an
>>>> aluminium can with 2 power leads coming out with 6 pin female
>>>> connectors on the end which go to the power board as used in the HP
>>>> Z3801 GPSDO and 2 thin coax cables with SMB connectors - one marked as
>>>> 10 MHz and the other as EFC. I may have to replace mine with the model
>>>> that has the tuning capacitor.
>>>>
>>>> Thanks for your response.
>>>>
>>>> 73 Merv
>>>>
>>>> On 29/08/2022 12:45 pm, Bill Beam via time-nuts wrote:
>>>>> I also run a Brooks Shera/HP 10811. Still going after many years.
>>>>> You must live with the limited steering voltage.
>>>>> The solution is to adjust the HP 10811 tuning capacitor to get it
>>>>> back near a frequency that the EFC can handle.
>>>>> I have had to do this more than once. Also if replacing the
>>>>> oscillator its tuning capacitor may need adjustment.
>>>>>
>>>>> On Mon, 29 Aug 2022 11:25:26 +0800, Mervyn Thomas via time-nuts wrote:
>>>>>
>>>>>> Hi All,
>>>>>> I'm new to time nuts but here goes.
>>>>>> I built a GPS disciplined- 10MHz osc about 15 + years ago.- It
>>>>>> uses an HP 10811 D/Oven Oscillator and the Brooks Shera PCB and
>>>>>> software V402N.- The physical construction article was per James
>>>>>> Miller G3RUH. This unit has worked flawlessly for all these years
>>>>>> but now is unable to hold the freq to precisely 10MHz - it is
>>>>>> constantly .29 to.60 Hz high.- The DAC output which controls the EFC
>>>>>> into the osc outputs a negative only adjustable voltage between -3v
>>>>>> down to 0V and is settable by varying a 10K potentiometer.- The
>>>>>> Osc. now needs abouit +0.46V to bring it down to 10MHz but the DAC
>>>>>> does not seem able to output a positive voltage.- The DAC is an
>>>>>> AD1861 (obsolete) and has a +5V applied to pin 16 and a -5V applied
>>>>>> to pins 1 and 8. My first reaction was the HP osc. had reached the
>>>>>> end of it's life but the datasheet states the EFC control voltage
>>>>>> can be between a plus 5V and a minus 5V which varies the freq by 1Hz
>>>>>> so it seems it is just over half way through it's life.
>>>>>> I feel the Brooks s/ware would have provided some method to ensure
>>>>>> the DAC output could be adjusted to swing the full full 5V or at
>>>>>> least 3V?- I have the source code but I'm no programmer so would
>>>>>> appreciate any help someone can provide please.
>>>>>> 73 de Merv- VK6BMT
>>>>>> _______________________________________________
>>>>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>>>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>>>>> Bill Beam
>>>>> NL7F
>>>>>
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>>>> _______________________________________________
>>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>>> _______________________________________________
>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>> _______________________________________________
>> time-nuts mailing list -- time-nuts@lists.febo.com
>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
> _______________________________________________
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe send an email to time-nuts-leave@lists.febo.com
DG
David G. McGaw
Wed, Aug 31, 2022 5:04 PM
Silver Oxide cells are pretty stable and are used as a replacement for
the older mercury cells that made good voltage references. One will
give you an additional 1.5V range.
David N1HAC
On 8/30/22 2:59 PM, Bob kb8tq via time-nuts wrote:
Hi
If you check the 10811 schematic, the varicap is biased at roughly +6.8V internally.
The other side of the diode is what the EFC is driving. This gives them the +/- 5V
range they specify on the 10811 data sheet.
Bob
On Aug 30, 2022, at 5:39 AM, paul swed via time-nuts time-nuts@lists.febo.com wrote:
Pretty clever approach to establishing an offset. But doesn't it matter how
the vari-cap is hooked up in the oscillator circuit? If the veri-cap needs
a negative voltage to work that may indicate the cathode is at ground and
the positive voltage would forward bias the vari-cap. Just thinking about
the possible impact.
Though the cost of experimenting is $0. No harm.
Regards
Paul
WB8TSL
On Tue, Aug 30, 2022 at 1:22 AM Mervyn Thomas via time-nuts <
time-nuts@lists.febo.com> wrote:
Stephen,
An idea I may try -thanks for your response. The current involved in
the EFC line to the oscillator is extremely small-button cells would
last years.
Merv
On 29/08/2022 8:42 pm, Stephen C. Menasian via time-nuts wrote:
Merv,
If I understand your problem, the 10811's VCO control input voltage has
drifted above the output range of the GPSD driver board. If the VCO
control terminal current is low enough, you might be able to quickly
this problem by putting 1 or 2 Lithium Ion Coin cells in series with the
control lead. If only a few microamperes are involved, this solutin might
last several years.
Stephen Menasian
On Mon, 29 Aug 2022 15:56:52 +0800
Mervyn Thomas via time-nuts time-nuts@lists.febo.com wrote:
Hi Bill,
Unfortunately the 2 HP 10811's I have have no way to poke anything thru
the can to adjust a capacitor. They are completely enclosed in an
aluminium can with 2 power leads coming out with 6 pin female
connectors on the end which go to the power board as used in the HP
Z3801 GPSDO and 2 thin coax cables with SMB connectors - one marked as
10 MHz and the other as EFC. I may have to replace mine with the model
that has the tuning capacitor.
Thanks for your response.
73 Merv
On 29/08/2022 12:45 pm, Bill Beam via time-nuts wrote:
I also run a Brooks Shera/HP 10811. Still going after many years.
You must live with the limited steering voltage.
The solution is to adjust the HP 10811 tuning capacitor to get it
back near a frequency that the EFC can handle.
I have had to do this more than once. Also if replacing the
oscillator its tuning capacitor may need adjustment.
On Mon, 29 Aug 2022 11:25:26 +0800, Mervyn Thomas via time-nuts wrote:
Hi All,
I'm new to time nuts but here goes.
I built a GPS disciplined- 10MHz osc about 15 + years ago.- It
uses an HP 10811 D/Oven Oscillator and the Brooks Shera PCB and
software V402N.- The physical construction article was per James
Miller G3RUH. This unit has worked flawlessly for all these years
but now is unable to hold the freq to precisely 10MHz - it is
constantly .29 to.60 Hz high.- The DAC output which controls the EFC
into the osc outputs a negative only adjustable voltage between -3v
down to 0V and is settable by varying a 10K potentiometer.- The
Osc. now needs abouit +0.46V to bring it down to 10MHz but the DAC
does not seem able to output a positive voltage.- The DAC is an
AD1861 (obsolete) and has a +5V applied to pin 16 and a -5V applied
to pins 1 and 8. My first reaction was the HP osc. had reached the
end of it's life but the datasheet states the EFC control voltage
can be between a plus 5V and a minus 5V which varies the freq by 1Hz
so it seems it is just over half way through it's life.
I feel the Brooks s/ware would have provided some method to ensure
the DAC output could be adjusted to swing the full full 5V or at
least 3V?- I have the source code but I'm no programmer so would
appreciate any help someone can provide please.
73 de Merv- VK6BMT
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
Silver Oxide cells are pretty stable and are used as a replacement for
the older mercury cells that made good voltage references. One will
give you an additional 1.5V range.
David N1HAC
On 8/30/22 2:59 PM, Bob kb8tq via time-nuts wrote:
> Hi
>
> If you check the 10811 schematic, the varicap is biased at roughly +6.8V internally.
> The other side of the diode is what the EFC is driving. This gives them the +/- 5V
> range they specify on the 10811 data sheet.
>
> Bob
>
>> On Aug 30, 2022, at 5:39 AM, paul swed via time-nuts <time-nuts@lists.febo.com> wrote:
>>
>> Pretty clever approach to establishing an offset. But doesn't it matter how
>> the vari-cap is hooked up in the oscillator circuit? If the veri-cap needs
>> a negative voltage to work that may indicate the cathode is at ground and
>> the positive voltage would forward bias the vari-cap. Just thinking about
>> the possible impact.
>> Though the cost of experimenting is $0. No harm.
>> Regards
>> Paul
>> WB8TSL
>>
>> On Tue, Aug 30, 2022 at 1:22 AM Mervyn Thomas via time-nuts <
>> time-nuts@lists.febo.com> wrote:
>>
>>> Stephen,
>>>
>>> An idea I may try -thanks for your response. The current involved in
>>> the EFC line to the oscillator is extremely small-button cells would
>>> last years.
>>>
>>> Merv
>>>
>>> On 29/08/2022 8:42 pm, Stephen C. Menasian via time-nuts wrote:
>>>> Merv,
>>>>
>>>> If I understand your problem, the 10811's VCO control input voltage has
>>>> drifted above the output range of the GPSD driver board. If the VCO
>>>> control terminal current is low enough, you might be able to quickly
>>> solve
>>>> this problem by putting 1 or 2 Lithium Ion Coin cells in series with the
>>>> control lead. If only a few microamperes are involved, this solutin might
>>>> last several years.
>>>>
>>>> Stephen Menasian
>>>>
>>>> On Mon, 29 Aug 2022 15:56:52 +0800
>>>> Mervyn Thomas via time-nuts <time-nuts@lists.febo.com> wrote:
>>>>
>>>>> Hi Bill,
>>>>>
>>>>> Unfortunately the 2 HP 10811's I have have no way to poke anything thru
>>>>> the can to adjust a capacitor. They are completely enclosed in an
>>>>> aluminium can with 2 power leads coming out with 6 pin female
>>>>> connectors on the end which go to the power board as used in the HP
>>>>> Z3801 GPSDO and 2 thin coax cables with SMB connectors - one marked as
>>>>> 10 MHz and the other as EFC. I may have to replace mine with the model
>>>>> that has the tuning capacitor.
>>>>>
>>>>> Thanks for your response.
>>>>>
>>>>> 73 Merv
>>>>>
>>>>> On 29/08/2022 12:45 pm, Bill Beam via time-nuts wrote:
>>>>>> I also run a Brooks Shera/HP 10811. Still going after many years.
>>>>>> You must live with the limited steering voltage.
>>>>>> The solution is to adjust the HP 10811 tuning capacitor to get it
>>>>>> back near a frequency that the EFC can handle.
>>>>>> I have had to do this more than once. Also if replacing the
>>>>>> oscillator its tuning capacitor may need adjustment.
>>>>>>
>>>>>> On Mon, 29 Aug 2022 11:25:26 +0800, Mervyn Thomas via time-nuts wrote:
>>>>>>
>>>>>>> Hi All,
>>>>>>> I'm new to time nuts but here goes.
>>>>>>> I built a GPS disciplined- 10MHz osc about 15 + years ago.- It
>>>>>>> uses an HP 10811 D/Oven Oscillator and the Brooks Shera PCB and
>>>>>>> software V402N.- The physical construction article was per James
>>>>>>> Miller G3RUH. This unit has worked flawlessly for all these years
>>>>>>> but now is unable to hold the freq to precisely 10MHz - it is
>>>>>>> constantly .29 to.60 Hz high.- The DAC output which controls the EFC
>>>>>>> into the osc outputs a negative only adjustable voltage between -3v
>>>>>>> down to 0V and is settable by varying a 10K potentiometer.- The
>>>>>>> Osc. now needs abouit +0.46V to bring it down to 10MHz but the DAC
>>>>>>> does not seem able to output a positive voltage.- The DAC is an
>>>>>>> AD1861 (obsolete) and has a +5V applied to pin 16 and a -5V applied
>>>>>>> to pins 1 and 8. My first reaction was the HP osc. had reached the
>>>>>>> end of it's life but the datasheet states the EFC control voltage
>>>>>>> can be between a plus 5V and a minus 5V which varies the freq by 1Hz
>>>>>>> so it seems it is just over half way through it's life.
>>>>>>> I feel the Brooks s/ware would have provided some method to ensure
>>>>>>> the DAC output could be adjusted to swing the full full 5V or at
>>>>>>> least 3V?- I have the source code but I'm no programmer so would
>>>>>>> appreciate any help someone can provide please.
>>>>>>> 73 de Merv- VK6BMT
>>>>>>> _______________________________________________
>>>>>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>>>>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>>>>>> Bill Beam
>>>>>> NL7F
>>>>>>
>>>>>>
>>>>>>
>>>>>> _______________________________________________
>>>>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>>>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>>>>> _______________________________________________
>>>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>>>> _______________________________________________
>>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>>> _______________________________________________
>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>> _______________________________________________
>> time-nuts mailing list -- time-nuts@lists.febo.com
>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
> _______________________________________________
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe send an email to time-nuts-leave@lists.febo.com
MT
Mervyn Thomas
Thu, Sep 1, 2022 7:21 AM
Hi Bob,
I need to find a schematic to download for my particular version of the
HP oscillator
Merv
On 31/08/2022 2:59 am, Bob kb8tq via time-nuts wrote:
Hi
If you check the 10811 schematic, the varicap is biased at roughly +6.8V internally.
The other side of the diode is what the EFC is driving. This gives them the +/- 5V
range they specify on the 10811 data sheet.
Bob
On Aug 30, 2022, at 5:39 AM, paul swed via time-nuts time-nuts@lists.febo.com wrote:
Pretty clever approach to establishing an offset. But doesn't it matter how
the vari-cap is hooked up in the oscillator circuit? If the veri-cap needs
a negative voltage to work that may indicate the cathode is at ground and
the positive voltage would forward bias the vari-cap. Just thinking about
the possible impact.
Though the cost of experimenting is $0. No harm.
Regards
Paul
WB8TSL
On Tue, Aug 30, 2022 at 1:22 AM Mervyn Thomas via time-nuts <
time-nuts@lists.febo.com> wrote:
Stephen,
An idea I may try -thanks for your response. The current involved in
the EFC line to the oscillator is extremely small-button cells would
last years.
Merv
On 29/08/2022 8:42 pm, Stephen C. Menasian via time-nuts wrote:
Merv,
If I understand your problem, the 10811's VCO control input voltage has
drifted above the output range of the GPSD driver board. If the VCO
control terminal current is low enough, you might be able to quickly
solve
this problem by putting 1 or 2 Lithium Ion Coin cells in series with the
control lead. If only a few microamperes are involved, this solutin might
last several years.
Stephen Menasian
On Mon, 29 Aug 2022 15:56:52 +0800
Mervyn Thomas via time-nuts time-nuts@lists.febo.com wrote:
Hi Bill,
Unfortunately the 2 HP 10811's I have have no way to poke anything thru
the can to adjust a capacitor. They are completely enclosed in an
aluminium can with 2 power leads coming out with 6 pin female
connectors on the end which go to the power board as used in the HP
Z3801 GPSDO and 2 thin coax cables with SMB connectors - one marked as
10 MHz and the other as EFC. I may have to replace mine with the model
that has the tuning capacitor.
Thanks for your response.
73 Merv
On 29/08/2022 12:45 pm, Bill Beam via time-nuts wrote:
I also run a Brooks Shera/HP 10811. Still going after many years.
You must live with the limited steering voltage.
The solution is to adjust the HP 10811 tuning capacitor to get it
back near a frequency that the EFC can handle.
I have had to do this more than once. Also if replacing the
oscillator its tuning capacitor may need adjustment.
On Mon, 29 Aug 2022 11:25:26 +0800, Mervyn Thomas via time-nuts wrote:
Hi All,
I'm new to time nuts but here goes.
I built a GPS disciplined- 10MHz osc about 15 + years ago.- It
uses an HP 10811 D/Oven Oscillator and the Brooks Shera PCB and
software V402N.- The physical construction article was per James
Miller G3RUH. This unit has worked flawlessly for all these years
but now is unable to hold the freq to precisely 10MHz - it is
constantly .29 to.60 Hz high.- The DAC output which controls the EFC
into the osc outputs a negative only adjustable voltage between -3v
down to 0V and is settable by varying a 10K potentiometer.- The
Osc. now needs abouit +0.46V to bring it down to 10MHz but the DAC
does not seem able to output a positive voltage.- The DAC is an
AD1861 (obsolete) and has a +5V applied to pin 16 and a -5V applied
to pins 1 and 8. My first reaction was the HP osc. had reached the
end of it's life but the datasheet states the EFC control voltage
can be between a plus 5V and a minus 5V which varies the freq by 1Hz
so it seems it is just over half way through it's life.
I feel the Brooks s/ware would have provided some method to ensure
the DAC output could be adjusted to swing the full full 5V or at
least 3V?- I have the source code but I'm no programmer so would
appreciate any help someone can provide please.
73 de Merv- VK6BMT
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
Bill Beam
NL7F
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
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To unsubscribe send an email to time-nuts-leave@lists.febo.com
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To unsubscribe send an email to time-nuts-leave@lists.febo.com
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To unsubscribe send an email to time-nuts-leave@lists.febo.com
Hi Bob,
I need to find a schematic to download for my particular version of the
HP oscillator
Merv
On 31/08/2022 2:59 am, Bob kb8tq via time-nuts wrote:
> Hi
>
> If you check the 10811 schematic, the varicap is biased at roughly +6.8V internally.
> The other side of the diode is what the EFC is driving. This gives them the +/- 5V
> range they specify on the 10811 data sheet.
>
> Bob
>
>> On Aug 30, 2022, at 5:39 AM, paul swed via time-nuts <time-nuts@lists.febo.com> wrote:
>>
>> Pretty clever approach to establishing an offset. But doesn't it matter how
>> the vari-cap is hooked up in the oscillator circuit? If the veri-cap needs
>> a negative voltage to work that may indicate the cathode is at ground and
>> the positive voltage would forward bias the vari-cap. Just thinking about
>> the possible impact.
>> Though the cost of experimenting is $0. No harm.
>> Regards
>> Paul
>> WB8TSL
>>
>> On Tue, Aug 30, 2022 at 1:22 AM Mervyn Thomas via time-nuts <
>> time-nuts@lists.febo.com> wrote:
>>
>>> Stephen,
>>>
>>> An idea I may try -thanks for your response. The current involved in
>>> the EFC line to the oscillator is extremely small-button cells would
>>> last years.
>>>
>>> Merv
>>>
>>> On 29/08/2022 8:42 pm, Stephen C. Menasian via time-nuts wrote:
>>>> Merv,
>>>>
>>>> If I understand your problem, the 10811's VCO control input voltage has
>>>> drifted above the output range of the GPSD driver board. If the VCO
>>>> control terminal current is low enough, you might be able to quickly
>>> solve
>>>> this problem by putting 1 or 2 Lithium Ion Coin cells in series with the
>>>> control lead. If only a few microamperes are involved, this solutin might
>>>> last several years.
>>>>
>>>> Stephen Menasian
>>>>
>>>> On Mon, 29 Aug 2022 15:56:52 +0800
>>>> Mervyn Thomas via time-nuts <time-nuts@lists.febo.com> wrote:
>>>>
>>>>> Hi Bill,
>>>>>
>>>>> Unfortunately the 2 HP 10811's I have have no way to poke anything thru
>>>>> the can to adjust a capacitor. They are completely enclosed in an
>>>>> aluminium can with 2 power leads coming out with 6 pin female
>>>>> connectors on the end which go to the power board as used in the HP
>>>>> Z3801 GPSDO and 2 thin coax cables with SMB connectors - one marked as
>>>>> 10 MHz and the other as EFC. I may have to replace mine with the model
>>>>> that has the tuning capacitor.
>>>>>
>>>>> Thanks for your response.
>>>>>
>>>>> 73 Merv
>>>>>
>>>>> On 29/08/2022 12:45 pm, Bill Beam via time-nuts wrote:
>>>>>> I also run a Brooks Shera/HP 10811. Still going after many years.
>>>>>> You must live with the limited steering voltage.
>>>>>> The solution is to adjust the HP 10811 tuning capacitor to get it
>>>>>> back near a frequency that the EFC can handle.
>>>>>> I have had to do this more than once. Also if replacing the
>>>>>> oscillator its tuning capacitor may need adjustment.
>>>>>>
>>>>>> On Mon, 29 Aug 2022 11:25:26 +0800, Mervyn Thomas via time-nuts wrote:
>>>>>>
>>>>>>> Hi All,
>>>>>>> I'm new to time nuts but here goes.
>>>>>>> I built a GPS disciplined- 10MHz osc about 15 + years ago.- It
>>>>>>> uses an HP 10811 D/Oven Oscillator and the Brooks Shera PCB and
>>>>>>> software V402N.- The physical construction article was per James
>>>>>>> Miller G3RUH. This unit has worked flawlessly for all these years
>>>>>>> but now is unable to hold the freq to precisely 10MHz - it is
>>>>>>> constantly .29 to.60 Hz high.- The DAC output which controls the EFC
>>>>>>> into the osc outputs a negative only adjustable voltage between -3v
>>>>>>> down to 0V and is settable by varying a 10K potentiometer.- The
>>>>>>> Osc. now needs abouit +0.46V to bring it down to 10MHz but the DAC
>>>>>>> does not seem able to output a positive voltage.- The DAC is an
>>>>>>> AD1861 (obsolete) and has a +5V applied to pin 16 and a -5V applied
>>>>>>> to pins 1 and 8. My first reaction was the HP osc. had reached the
>>>>>>> end of it's life but the datasheet states the EFC control voltage
>>>>>>> can be between a plus 5V and a minus 5V which varies the freq by 1Hz
>>>>>>> so it seems it is just over half way through it's life.
>>>>>>> I feel the Brooks s/ware would have provided some method to ensure
>>>>>>> the DAC output could be adjusted to swing the full full 5V or at
>>>>>>> least 3V?- I have the source code but I'm no programmer so would
>>>>>>> appreciate any help someone can provide please.
>>>>>>> 73 de Merv- VK6BMT
>>>>>>> _______________________________________________
>>>>>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>>>>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>>>>>> Bill Beam
>>>>>> NL7F
>>>>>>
>>>>>>
>>>>>>
>>>>>> _______________________________________________
>>>>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>>>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>>>>> _______________________________________________
>>>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>>>> _______________________________________________
>>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>>> _______________________________________________
>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>> _______________________________________________
>> time-nuts mailing list -- time-nuts@lists.febo.com
>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
> _______________________________________________
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe send an email to time-nuts-leave@lists.febo.com
MT
Mervyn Thomas
Thu, Sep 1, 2022 7:30 AM
Steve,
It has a glue on label stating it's Serial Number but unfortunately no
hole under it. The bench power supply I'm using reads current down to
1000th of an amp but not down to uA so a good suggestion I put a
microamp meter in series to see what current is being drawn.
Thanks, Merv
On 30/08/2022 10:27 pm, Stephen C. Menasian via time-nuts wrote:
Paul,
That is a valid consideration. Unfortunately, I don't have a schematic of
the oscillator and can't say, definitely, whether is relevant. In trying
this out, I would start with an adjustable DC power supply with a
microammeter in series with its output and monitor the current as the
voltage is increased from zero. This would be necessary, anyway, to
estimate the expected cell life. A current rise resembling a a diode
turn-on knee would serve to establish the limit. I wouldn't ever let it
rise above 1 mA or so. Some varactors have MAX forward currents in the
10s of mA range. If the knee is found at a voltage below the Li ion
coin cell range, a 1.5 Volt cell might be in order. Also, I would monitor
the oscillator output frequency as I did this. After all, if one can't
reach 10 MHz without forward biasing the varactor, the only course of
action might be to cut the oscillator can open.
Something occurred to me. Does the oscillator have a glued-on label?
Sometimes these are used to cover access holes to "factory-only"
adjustments. One can often locate this type of hole with ones finger
by pressing on the label and feeling for a depression.
Stephen
On Tue, 30 Aug 2022 09:39:36 -0400
paul swed via time-nuts time-nuts@lists.febo.com wrote:
Pretty clever approach to establishing an offset. But doesn't it matter
how the vari-cap is hooked up in the oscillator circuit? If the
veri-cap needs a negative voltage to work that may indicate the cathode
is at ground and the positive voltage would forward bias the vari-cap.
Just thinking about the possible impact.
Though the cost of experimenting is $0. No harm.
Regards
Paul
WB8TSL
On Tue, Aug 30, 2022 at 1:22 AM Mervyn Thomas via time-nuts <
time-nuts@lists.febo.com> wrote:
Stephen,
An idea I may try -thanks for your response. The current involved in
the EFC line to the oscillator is extremely small-button cells would
last years.
Merv
On 29/08/2022 8:42 pm, Stephen C. Menasian via time-nuts wrote:
Merv,
If I understand your problem, the 10811's VCO control input voltage
has drifted above the output range of the GPSD driver board. If the
VCO control terminal current is low enough, you might be able to
quickly
solve
this problem by putting 1 or 2 Lithium Ion Coin cells in series
with the control lead. If only a few microamperes are involved,
this solutin might last several years.
Stephen Menasian
On Mon, 29 Aug 2022 15:56:52 +0800
Mervyn Thomas via time-nuts time-nuts@lists.febo.com wrote:
Hi Bill,
Unfortunately the 2 HP 10811's I have have no way to poke anything
thru the can to adjust a capacitor. They are completely enclosed
in an aluminium can with 2 power leads coming out with 6 pin female
connectors on the end which go to the power board as used in the HP
Z3801 GPSDO and 2 thin coax cables with SMB connectors - one
marked as 10 MHz and the other as EFC. I may have to replace mine
with the model that has the tuning capacitor.
Thanks for your response.
73 Merv
On 29/08/2022 12:45 pm, Bill Beam via time-nuts wrote:
I also run a Brooks Shera/HP 10811. Still going after many years.
You must live with the limited steering voltage.
The solution is to adjust the HP 10811 tuning capacitor to get it
back near a frequency that the EFC can handle.
I have had to do this more than once. Also if replacing the
oscillator its tuning capacitor may need adjustment.
On Mon, 29 Aug 2022 11:25:26 +0800, Mervyn Thomas via time-nuts
wrote:
Hi All,
I'm new to time nuts but here goes.
I built a GPS disciplined- 10MHz osc about 15 + years ago.- It
uses an HP 10811 D/Oven Oscillator and the Brooks Shera PCB and
software V402N.- The physical construction article was per James
Miller G3RUH. This unit has worked flawlessly for all these years
but now is unable to hold the freq to precisely 10MHz - it is
constantly .29 to.60 Hz high.- The DAC output which controls the
EFC into the osc outputs a negative only adjustable voltage
between -3v down to 0V and is settable by varying a 10K
potentiometer.- The Osc. now needs abouit +0.46V to bring it
down to 10MHz but the DAC does not seem able to output a
positive voltage.- The DAC is an AD1861 (obsolete) and has a
+5V applied to pin 16 and a -5V applied to pins 1 and 8. My
first reaction was the HP osc. had reached the end of it's life
but the datasheet states the EFC control voltage can be between
a plus 5V and a minus 5V which varies the freq by 1Hz so it
seems it is just over half way through it's life. I feel the
Brooks s/ware would have provided some method to ensure the DAC
output could be adjusted to swing the full full 5V or at least
3V?- I have the source code but I'm no programmer so would
appreciate any help someone can provide please. 73 de Merv-
VK6BMT _______________________________________________
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
Bill Beam
NL7F
time-nuts mailing list -- time-nuts@lists.febo.com
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Steve,
It has a glue on label stating it's Serial Number but unfortunately no
hole under it. The bench power supply I'm using reads current down to
1000th of an amp but not down to uA so a good suggestion I put a
microamp meter in series to see what current is being drawn.
Thanks, Merv
On 30/08/2022 10:27 pm, Stephen C. Menasian via time-nuts wrote:
> Paul,
>
> That is a valid consideration. Unfortunately, I don't have a schematic of
> the oscillator and can't say, definitely, whether is relevant. In trying
> this out, I would start with an adjustable DC power supply with a
> microammeter in series with its output and monitor the current as the
> voltage is increased from zero. This would be necessary, anyway, to
> estimate the expected cell life. A current rise resembling a a diode
> turn-on knee would serve to establish the limit. I wouldn't ever let it
> rise above 1 mA or so. Some varactors have MAX forward currents in the
> 10s of mA range. If the knee is found at a voltage below the Li ion
> coin cell range, a 1.5 Volt cell might be in order. Also, I would monitor
> the oscillator output frequency as I did this. After all, if one can't
> reach 10 MHz without forward biasing the varactor, the only course of
> action might be to cut the oscillator can open.
>
> Something occurred to me. Does the oscillator have a glued-on label?
> Sometimes these are used to cover access holes to "factory-only"
> adjustments. One can often locate this type of hole with ones finger
> by pressing on the label and feeling for a depression.
>
> Stephen
>
>
> On Tue, 30 Aug 2022 09:39:36 -0400
> paul swed via time-nuts <time-nuts@lists.febo.com> wrote:
>
>> Pretty clever approach to establishing an offset. But doesn't it matter
>> how the vari-cap is hooked up in the oscillator circuit? If the
>> veri-cap needs a negative voltage to work that may indicate the cathode
>> is at ground and the positive voltage would forward bias the vari-cap.
>> Just thinking about the possible impact.
>> Though the cost of experimenting is $0. No harm.
>> Regards
>> Paul
>> WB8TSL
>>
>> On Tue, Aug 30, 2022 at 1:22 AM Mervyn Thomas via time-nuts <
>> time-nuts@lists.febo.com> wrote:
>>
>>> Stephen,
>>>
>>> An idea I may try -thanks for your response. The current involved in
>>> the EFC line to the oscillator is extremely small-button cells would
>>> last years.
>>>
>>> Merv
>>>
>>> On 29/08/2022 8:42 pm, Stephen C. Menasian via time-nuts wrote:
>>>> Merv,
>>>>
>>>> If I understand your problem, the 10811's VCO control input voltage
>>>> has drifted above the output range of the GPSD driver board. If the
>>>> VCO control terminal current is low enough, you might be able to
>>>> quickly
>>> solve
>>>> this problem by putting 1 or 2 Lithium Ion Coin cells in series
>>>> with the control lead. If only a few microamperes are involved,
>>>> this solutin might last several years.
>>>>
>>>> Stephen Menasian
>>>>
>>>> On Mon, 29 Aug 2022 15:56:52 +0800
>>>> Mervyn Thomas via time-nuts <time-nuts@lists.febo.com> wrote:
>>>>
>>>>> Hi Bill,
>>>>>
>>>>> Unfortunately the 2 HP 10811's I have have no way to poke anything
>>>>> thru the can to adjust a capacitor. They are completely enclosed
>>>>> in an aluminium can with 2 power leads coming out with 6 pin female
>>>>> connectors on the end which go to the power board as used in the HP
>>>>> Z3801 GPSDO and 2 thin coax cables with SMB connectors - one
>>>>> marked as 10 MHz and the other as EFC. I may have to replace mine
>>>>> with the model that has the tuning capacitor.
>>>>>
>>>>> Thanks for your response.
>>>>>
>>>>> 73 Merv
>>>>>
>>>>> On 29/08/2022 12:45 pm, Bill Beam via time-nuts wrote:
>>>>>> I also run a Brooks Shera/HP 10811. Still going after many years.
>>>>>> You must live with the limited steering voltage.
>>>>>> The solution is to adjust the HP 10811 tuning capacitor to get it
>>>>>> back near a frequency that the EFC can handle.
>>>>>> I have had to do this more than once. Also if replacing the
>>>>>> oscillator its tuning capacitor may need adjustment.
>>>>>>
>>>>>> On Mon, 29 Aug 2022 11:25:26 +0800, Mervyn Thomas via time-nuts
>>>>>> wrote:
>>>>>>> Hi All,
>>>>>>> I'm new to time nuts but here goes.
>>>>>>> I built a GPS disciplined- 10MHz osc about 15 + years ago.- It
>>>>>>> uses an HP 10811 D/Oven Oscillator and the Brooks Shera PCB and
>>>>>>> software V402N.- The physical construction article was per James
>>>>>>> Miller G3RUH. This unit has worked flawlessly for all these years
>>>>>>> but now is unable to hold the freq to precisely 10MHz - it is
>>>>>>> constantly .29 to.60 Hz high.- The DAC output which controls the
>>>>>>> EFC into the osc outputs a negative only adjustable voltage
>>>>>>> between -3v down to 0V and is settable by varying a 10K
>>>>>>> potentiometer.- The Osc. now needs abouit +0.46V to bring it
>>>>>>> down to 10MHz but the DAC does not seem able to output a
>>>>>>> positive voltage.- The DAC is an AD1861 (obsolete) and has a
>>>>>>> +5V applied to pin 16 and a -5V applied to pins 1 and 8. My
>>>>>>> first reaction was the HP osc. had reached the end of it's life
>>>>>>> but the datasheet states the EFC control voltage can be between
>>>>>>> a plus 5V and a minus 5V which varies the freq by 1Hz so it
>>>>>>> seems it is just over half way through it's life. I feel the
>>>>>>> Brooks s/ware would have provided some method to ensure the DAC
>>>>>>> output could be adjusted to swing the full full 5V or at least
>>>>>>> 3V?- I have the source code but I'm no programmer so would
>>>>>>> appreciate any help someone can provide please. 73 de Merv-
>>>>>>> VK6BMT _______________________________________________
>>>>>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>>>>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>>>>>> Bill Beam
>>>>>> NL7F
>>>>>>
>>>>>>
>>>>>>
>>>>>> _______________________________________________
>>>>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>>>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>>>>> _______________________________________________
>>>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>>>> _______________________________________________
>>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>>> _______________________________________________
>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>> _______________________________________________
>> time-nuts mailing list -- time-nuts@lists.febo.com
>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>>
> _______________________________________________
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe send an email to time-nuts-leave@lists.febo.com
BK
Bob kb8tq
Thu, Sep 1, 2022 8:55 PM
Hi
The version you have simply has a “box” around a fairly normal
10811 OCXO. Tearing it apart is possible. It isn’t a whole lot of fun
though.
I still believe that the GPSDO board should put out +/- voltages
and not just a negative voltage. Positive tune voltages are pretty
common. Bipolar tune is unusual but not unheard of. Negative
only tune is very rare. Since the board is already out in the open,
working on it should be easier than ripping open the OCXO.
Bob
On Aug 31, 2022, at 11:21 PM, Mervyn Thomas via time-nuts time-nuts@lists.febo.com wrote:
Hi Bob,
I need to find a schematic to download for my particular version of the HP oscillator
Merv
On 31/08/2022 2:59 am, Bob kb8tq via time-nuts wrote:
Hi
If you check the 10811 schematic, the varicap is biased at roughly +6.8V internally.
The other side of the diode is what the EFC is driving. This gives them the +/- 5V
range they specify on the 10811 data sheet.
Bob
On Aug 30, 2022, at 5:39 AM, paul swed via time-nuts time-nuts@lists.febo.com wrote:
Pretty clever approach to establishing an offset. But doesn't it matter how
the vari-cap is hooked up in the oscillator circuit? If the veri-cap needs
a negative voltage to work that may indicate the cathode is at ground and
the positive voltage would forward bias the vari-cap. Just thinking about
the possible impact.
Though the cost of experimenting is $0. No harm.
Regards
Paul
WB8TSL
On Tue, Aug 30, 2022 at 1:22 AM Mervyn Thomas via time-nuts <
time-nuts@lists.febo.com> wrote:
Stephen,
An idea I may try -thanks for your response. The current involved in
the EFC line to the oscillator is extremely small-button cells would
last years.
Merv
On 29/08/2022 8:42 pm, Stephen C. Menasian via time-nuts wrote:
Merv,
If I understand your problem, the 10811's VCO control input voltage has
drifted above the output range of the GPSD driver board. If the VCO
control terminal current is low enough, you might be able to quickly
this problem by putting 1 or 2 Lithium Ion Coin cells in series with the
control lead. If only a few microamperes are involved, this solutin might
last several years.
Stephen Menasian
On Mon, 29 Aug 2022 15:56:52 +0800
Mervyn Thomas via time-nuts time-nuts@lists.febo.com wrote:
Hi Bill,
Unfortunately the 2 HP 10811's I have have no way to poke anything thru
the can to adjust a capacitor. They are completely enclosed in an
aluminium can with 2 power leads coming out with 6 pin female
connectors on the end which go to the power board as used in the HP
Z3801 GPSDO and 2 thin coax cables with SMB connectors - one marked as
10 MHz and the other as EFC. I may have to replace mine with the model
that has the tuning capacitor.
Thanks for your response.
73 Merv
On 29/08/2022 12:45 pm, Bill Beam via time-nuts wrote:
I also run a Brooks Shera/HP 10811. Still going after many years.
You must live with the limited steering voltage.
The solution is to adjust the HP 10811 tuning capacitor to get it
back near a frequency that the EFC can handle.
I have had to do this more than once. Also if replacing the
oscillator its tuning capacitor may need adjustment.
On Mon, 29 Aug 2022 11:25:26 +0800, Mervyn Thomas via time-nuts wrote:
Hi All,
I'm new to time nuts but here goes.
I built a GPS disciplined- 10MHz osc about 15 + years ago.- It
uses an HP 10811 D/Oven Oscillator and the Brooks Shera PCB and
software V402N.- The physical construction article was per James
Miller G3RUH. This unit has worked flawlessly for all these years
but now is unable to hold the freq to precisely 10MHz - it is
constantly .29 to.60 Hz high.- The DAC output which controls the EFC
into the osc outputs a negative only adjustable voltage between -3v
down to 0V and is settable by varying a 10K potentiometer.- The
Osc. now needs abouit +0.46V to bring it down to 10MHz but the DAC
does not seem able to output a positive voltage.- The DAC is an
AD1861 (obsolete) and has a +5V applied to pin 16 and a -5V applied
to pins 1 and 8. My first reaction was the HP osc. had reached the
end of it's life but the datasheet states the EFC control voltage
can be between a plus 5V and a minus 5V which varies the freq by 1Hz
so it seems it is just over half way through it's life.
I feel the Brooks s/ware would have provided some method to ensure
the DAC output could be adjusted to swing the full full 5V or at
least 3V?- I have the source code but I'm no programmer so would
appreciate any help someone can provide please.
73 de Merv- VK6BMT
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
Hi
The version you have simply has a “box” around a fairly normal
10811 OCXO. Tearing it apart is possible. It isn’t a whole lot of fun
though.
I still believe that the GPSDO board should put out +/- voltages
and not just a negative voltage. Positive tune voltages are pretty
common. Bipolar tune is unusual but not unheard of. Negative
only tune is *very* rare. Since the board is already out in the open,
working on it should be easier than ripping open the OCXO.
Bob
> On Aug 31, 2022, at 11:21 PM, Mervyn Thomas via time-nuts <time-nuts@lists.febo.com> wrote:
>
> Hi Bob,
>
> I need to find a schematic to download for my particular version of the HP oscillator
>
> Merv
>
> On 31/08/2022 2:59 am, Bob kb8tq via time-nuts wrote:
>> Hi
>>
>> If you check the 10811 schematic, the varicap is biased at roughly +6.8V internally.
>> The other side of the diode is what the EFC is driving. This gives them the +/- 5V
>> range they specify on the 10811 data sheet.
>>
>> Bob
>>
>>> On Aug 30, 2022, at 5:39 AM, paul swed via time-nuts <time-nuts@lists.febo.com> wrote:
>>>
>>> Pretty clever approach to establishing an offset. But doesn't it matter how
>>> the vari-cap is hooked up in the oscillator circuit? If the veri-cap needs
>>> a negative voltage to work that may indicate the cathode is at ground and
>>> the positive voltage would forward bias the vari-cap. Just thinking about
>>> the possible impact.
>>> Though the cost of experimenting is $0. No harm.
>>> Regards
>>> Paul
>>> WB8TSL
>>>
>>> On Tue, Aug 30, 2022 at 1:22 AM Mervyn Thomas via time-nuts <
>>> time-nuts@lists.febo.com> wrote:
>>>
>>>> Stephen,
>>>>
>>>> An idea I may try -thanks for your response. The current involved in
>>>> the EFC line to the oscillator is extremely small-button cells would
>>>> last years.
>>>>
>>>> Merv
>>>>
>>>> On 29/08/2022 8:42 pm, Stephen C. Menasian via time-nuts wrote:
>>>>> Merv,
>>>>>
>>>>> If I understand your problem, the 10811's VCO control input voltage has
>>>>> drifted above the output range of the GPSD driver board. If the VCO
>>>>> control terminal current is low enough, you might be able to quickly
>>>> solve
>>>>> this problem by putting 1 or 2 Lithium Ion Coin cells in series with the
>>>>> control lead. If only a few microamperes are involved, this solutin might
>>>>> last several years.
>>>>>
>>>>> Stephen Menasian
>>>>>
>>>>> On Mon, 29 Aug 2022 15:56:52 +0800
>>>>> Mervyn Thomas via time-nuts <time-nuts@lists.febo.com> wrote:
>>>>>
>>>>>> Hi Bill,
>>>>>>
>>>>>> Unfortunately the 2 HP 10811's I have have no way to poke anything thru
>>>>>> the can to adjust a capacitor. They are completely enclosed in an
>>>>>> aluminium can with 2 power leads coming out with 6 pin female
>>>>>> connectors on the end which go to the power board as used in the HP
>>>>>> Z3801 GPSDO and 2 thin coax cables with SMB connectors - one marked as
>>>>>> 10 MHz and the other as EFC. I may have to replace mine with the model
>>>>>> that has the tuning capacitor.
>>>>>>
>>>>>> Thanks for your response.
>>>>>>
>>>>>> 73 Merv
>>>>>>
>>>>>> On 29/08/2022 12:45 pm, Bill Beam via time-nuts wrote:
>>>>>>> I also run a Brooks Shera/HP 10811. Still going after many years.
>>>>>>> You must live with the limited steering voltage.
>>>>>>> The solution is to adjust the HP 10811 tuning capacitor to get it
>>>>>>> back near a frequency that the EFC can handle.
>>>>>>> I have had to do this more than once. Also if replacing the
>>>>>>> oscillator its tuning capacitor may need adjustment.
>>>>>>>
>>>>>>> On Mon, 29 Aug 2022 11:25:26 +0800, Mervyn Thomas via time-nuts wrote:
>>>>>>>
>>>>>>>> Hi All,
>>>>>>>> I'm new to time nuts but here goes.
>>>>>>>> I built a GPS disciplined- 10MHz osc about 15 + years ago.- It
>>>>>>>> uses an HP 10811 D/Oven Oscillator and the Brooks Shera PCB and
>>>>>>>> software V402N.- The physical construction article was per James
>>>>>>>> Miller G3RUH. This unit has worked flawlessly for all these years
>>>>>>>> but now is unable to hold the freq to precisely 10MHz - it is
>>>>>>>> constantly .29 to.60 Hz high.- The DAC output which controls the EFC
>>>>>>>> into the osc outputs a negative only adjustable voltage between -3v
>>>>>>>> down to 0V and is settable by varying a 10K potentiometer.- The
>>>>>>>> Osc. now needs abouit +0.46V to bring it down to 10MHz but the DAC
>>>>>>>> does not seem able to output a positive voltage.- The DAC is an
>>>>>>>> AD1861 (obsolete) and has a +5V applied to pin 16 and a -5V applied
>>>>>>>> to pins 1 and 8. My first reaction was the HP osc. had reached the
>>>>>>>> end of it's life but the datasheet states the EFC control voltage
>>>>>>>> can be between a plus 5V and a minus 5V which varies the freq by 1Hz
>>>>>>>> so it seems it is just over half way through it's life.
>>>>>>>> I feel the Brooks s/ware would have provided some method to ensure
>>>>>>>> the DAC output could be adjusted to swing the full full 5V or at
>>>>>>>> least 3V?- I have the source code but I'm no programmer so would
>>>>>>>> appreciate any help someone can provide please.
>>>>>>>> 73 de Merv- VK6BMT
>>>>>>>> _______________________________________________
>>>>>>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>>>>>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>>>>>>> Bill Beam
>>>>>>> NL7F
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>>>>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>>>>>> _______________________________________________
>>>>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>>>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>>>>> _______________________________________________
>>>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>>>> _______________________________________________
>>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>>> _______________________________________________
>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>> _______________________________________________
>> time-nuts mailing list -- time-nuts@lists.febo.com
>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
> _______________________________________________
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe send an email to time-nuts-leave@lists.febo.com
MT
Mervyn Thomas
Fri, Sep 2, 2022 8:46 AM
Bob,
I'm with you on that and although I have 2 10811's I would be loathe to
tear one apart - certainly as a last resort only and for information
sake rather than being able to fix it.
Merv
On 2/09/2022 4:55 am, Bob kb8tq via time-nuts wrote:
Hi
The version you have simply has a “box” around a fairly normal
10811 OCXO. Tearing it apart is possible. It isn’t a whole lot of fun
though.
I still believe that the GPSDO board should put out +/- voltages
and not just a negative voltage. Positive tune voltages are pretty
common. Bipolar tune is unusual but not unheard of. Negative
only tune is very rare. Since the board is already out in the open,
working on it should be easier than ripping open the OCXO.
Bob
On Aug 31, 2022, at 11:21 PM, Mervyn Thomas via time-nuts time-nuts@lists.febo.com wrote:
Hi Bob,
I need to find a schematic to download for my particular version of the HP oscillator
Merv
On 31/08/2022 2:59 am, Bob kb8tq via time-nuts wrote:
Hi
If you check the 10811 schematic, the varicap is biased at roughly +6.8V internally.
The other side of the diode is what the EFC is driving. This gives them the +/- 5V
range they specify on the 10811 data sheet.
Bob
On Aug 30, 2022, at 5:39 AM, paul swed via time-nuts time-nuts@lists.febo.com wrote:
Pretty clever approach to establishing an offset. But doesn't it matter how
the vari-cap is hooked up in the oscillator circuit? If the veri-cap needs
a negative voltage to work that may indicate the cathode is at ground and
the positive voltage would forward bias the vari-cap. Just thinking about
the possible impact.
Though the cost of experimenting is $0. No harm.
Regards
Paul
WB8TSL
On Tue, Aug 30, 2022 at 1:22 AM Mervyn Thomas via time-nuts <
time-nuts@lists.febo.com> wrote:
Stephen,
An idea I may try -thanks for your response. The current involved in
the EFC line to the oscillator is extremely small-button cells would
last years.
Merv
On 29/08/2022 8:42 pm, Stephen C. Menasian via time-nuts wrote:
Merv,
If I understand your problem, the 10811's VCO control input voltage has
drifted above the output range of the GPSD driver board. If the VCO
control terminal current is low enough, you might be able to quickly
solve
this problem by putting 1 or 2 Lithium Ion Coin cells in series with the
control lead. If only a few microamperes are involved, this solutin might
last several years.
Stephen Menasian
On Mon, 29 Aug 2022 15:56:52 +0800
Mervyn Thomas via time-nuts time-nuts@lists.febo.com wrote:
Hi Bill,
Unfortunately the 2 HP 10811's I have have no way to poke anything thru
the can to adjust a capacitor. They are completely enclosed in an
aluminium can with 2 power leads coming out with 6 pin female
connectors on the end which go to the power board as used in the HP
Z3801 GPSDO and 2 thin coax cables with SMB connectors - one marked as
10 MHz and the other as EFC. I may have to replace mine with the model
that has the tuning capacitor.
Thanks for your response.
73 Merv
On 29/08/2022 12:45 pm, Bill Beam via time-nuts wrote:
I also run a Brooks Shera/HP 10811. Still going after many years.
You must live with the limited steering voltage.
The solution is to adjust the HP 10811 tuning capacitor to get it
back near a frequency that the EFC can handle.
I have had to do this more than once. Also if replacing the
oscillator its tuning capacitor may need adjustment.
On Mon, 29 Aug 2022 11:25:26 +0800, Mervyn Thomas via time-nuts wrote:
Hi All,
I'm new to time nuts but here goes.
I built a GPS disciplined- 10MHz osc about 15 + years ago.- It
uses an HP 10811 D/Oven Oscillator and the Brooks Shera PCB and
software V402N.- The physical construction article was per James
Miller G3RUH. This unit has worked flawlessly for all these years
but now is unable to hold the freq to precisely 10MHz - it is
constantly .29 to.60 Hz high.- The DAC output which controls the EFC
into the osc outputs a negative only adjustable voltage between -3v
down to 0V and is settable by varying a 10K potentiometer.- The
Osc. now needs abouit +0.46V to bring it down to 10MHz but the DAC
does not seem able to output a positive voltage.- The DAC is an
AD1861 (obsolete) and has a +5V applied to pin 16 and a -5V applied
to pins 1 and 8. My first reaction was the HP osc. had reached the
end of it's life but the datasheet states the EFC control voltage
can be between a plus 5V and a minus 5V which varies the freq by 1Hz
so it seems it is just over half way through it's life.
I feel the Brooks s/ware would have provided some method to ensure
the DAC output could be adjusted to swing the full full 5V or at
least 3V?- I have the source code but I'm no programmer so would
appreciate any help someone can provide please.
73 de Merv- VK6BMT
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
Bill Beam
NL7F
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Bob,
I'm with you on that and although I have 2 10811's I would be loathe to
tear one apart - certainly as a last resort only and for information
sake rather than being able to fix it.
Merv
On 2/09/2022 4:55 am, Bob kb8tq via time-nuts wrote:
> Hi
>
> The version you have simply has a “box” around a fairly normal
> 10811 OCXO. Tearing it apart is possible. It isn’t a whole lot of fun
> though.
>
> I still believe that the GPSDO board should put out +/- voltages
> and not just a negative voltage. Positive tune voltages are pretty
> common. Bipolar tune is unusual but not unheard of. Negative
> only tune is *very* rare. Since the board is already out in the open,
> working on it should be easier than ripping open the OCXO.
>
> Bob
>
>> On Aug 31, 2022, at 11:21 PM, Mervyn Thomas via time-nuts <time-nuts@lists.febo.com> wrote:
>>
>> Hi Bob,
>>
>> I need to find a schematic to download for my particular version of the HP oscillator
>>
>> Merv
>>
>> On 31/08/2022 2:59 am, Bob kb8tq via time-nuts wrote:
>>> Hi
>>>
>>> If you check the 10811 schematic, the varicap is biased at roughly +6.8V internally.
>>> The other side of the diode is what the EFC is driving. This gives them the +/- 5V
>>> range they specify on the 10811 data sheet.
>>>
>>> Bob
>>>
>>>> On Aug 30, 2022, at 5:39 AM, paul swed via time-nuts <time-nuts@lists.febo.com> wrote:
>>>>
>>>> Pretty clever approach to establishing an offset. But doesn't it matter how
>>>> the vari-cap is hooked up in the oscillator circuit? If the veri-cap needs
>>>> a negative voltage to work that may indicate the cathode is at ground and
>>>> the positive voltage would forward bias the vari-cap. Just thinking about
>>>> the possible impact.
>>>> Though the cost of experimenting is $0. No harm.
>>>> Regards
>>>> Paul
>>>> WB8TSL
>>>>
>>>> On Tue, Aug 30, 2022 at 1:22 AM Mervyn Thomas via time-nuts <
>>>> time-nuts@lists.febo.com> wrote:
>>>>
>>>>> Stephen,
>>>>>
>>>>> An idea I may try -thanks for your response. The current involved in
>>>>> the EFC line to the oscillator is extremely small-button cells would
>>>>> last years.
>>>>>
>>>>> Merv
>>>>>
>>>>> On 29/08/2022 8:42 pm, Stephen C. Menasian via time-nuts wrote:
>>>>>> Merv,
>>>>>>
>>>>>> If I understand your problem, the 10811's VCO control input voltage has
>>>>>> drifted above the output range of the GPSD driver board. If the VCO
>>>>>> control terminal current is low enough, you might be able to quickly
>>>>> solve
>>>>>> this problem by putting 1 or 2 Lithium Ion Coin cells in series with the
>>>>>> control lead. If only a few microamperes are involved, this solutin might
>>>>>> last several years.
>>>>>>
>>>>>> Stephen Menasian
>>>>>>
>>>>>> On Mon, 29 Aug 2022 15:56:52 +0800
>>>>>> Mervyn Thomas via time-nuts <time-nuts@lists.febo.com> wrote:
>>>>>>
>>>>>>> Hi Bill,
>>>>>>>
>>>>>>> Unfortunately the 2 HP 10811's I have have no way to poke anything thru
>>>>>>> the can to adjust a capacitor. They are completely enclosed in an
>>>>>>> aluminium can with 2 power leads coming out with 6 pin female
>>>>>>> connectors on the end which go to the power board as used in the HP
>>>>>>> Z3801 GPSDO and 2 thin coax cables with SMB connectors - one marked as
>>>>>>> 10 MHz and the other as EFC. I may have to replace mine with the model
>>>>>>> that has the tuning capacitor.
>>>>>>>
>>>>>>> Thanks for your response.
>>>>>>>
>>>>>>> 73 Merv
>>>>>>>
>>>>>>> On 29/08/2022 12:45 pm, Bill Beam via time-nuts wrote:
>>>>>>>> I also run a Brooks Shera/HP 10811. Still going after many years.
>>>>>>>> You must live with the limited steering voltage.
>>>>>>>> The solution is to adjust the HP 10811 tuning capacitor to get it
>>>>>>>> back near a frequency that the EFC can handle.
>>>>>>>> I have had to do this more than once. Also if replacing the
>>>>>>>> oscillator its tuning capacitor may need adjustment.
>>>>>>>>
>>>>>>>> On Mon, 29 Aug 2022 11:25:26 +0800, Mervyn Thomas via time-nuts wrote:
>>>>>>>>
>>>>>>>>> Hi All,
>>>>>>>>> I'm new to time nuts but here goes.
>>>>>>>>> I built a GPS disciplined- 10MHz osc about 15 + years ago.- It
>>>>>>>>> uses an HP 10811 D/Oven Oscillator and the Brooks Shera PCB and
>>>>>>>>> software V402N.- The physical construction article was per James
>>>>>>>>> Miller G3RUH. This unit has worked flawlessly for all these years
>>>>>>>>> but now is unable to hold the freq to precisely 10MHz - it is
>>>>>>>>> constantly .29 to.60 Hz high.- The DAC output which controls the EFC
>>>>>>>>> into the osc outputs a negative only adjustable voltage between -3v
>>>>>>>>> down to 0V and is settable by varying a 10K potentiometer.- The
>>>>>>>>> Osc. now needs abouit +0.46V to bring it down to 10MHz but the DAC
>>>>>>>>> does not seem able to output a positive voltage.- The DAC is an
>>>>>>>>> AD1861 (obsolete) and has a +5V applied to pin 16 and a -5V applied
>>>>>>>>> to pins 1 and 8. My first reaction was the HP osc. had reached the
>>>>>>>>> end of it's life but the datasheet states the EFC control voltage
>>>>>>>>> can be between a plus 5V and a minus 5V which varies the freq by 1Hz
>>>>>>>>> so it seems it is just over half way through it's life.
>>>>>>>>> I feel the Brooks s/ware would have provided some method to ensure
>>>>>>>>> the DAC output could be adjusted to swing the full full 5V or at
>>>>>>>>> least 3V?- I have the source code but I'm no programmer so would
>>>>>>>>> appreciate any help someone can provide please.
>>>>>>>>> 73 de Merv- VK6BMT
>>>>>>>>> _______________________________________________
>>>>>>>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>>>>>>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>>>>>>>> Bill Beam
>>>>>>>> NL7F
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> _______________________________________________
>>>>>>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>>>>>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>>>>>>> _______________________________________________
>>>>>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>>>>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>>>>>> _______________________________________________
>>>>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>>>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>>>>> _______________________________________________
>>>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>>>> _______________________________________________
>>>> time-nuts mailing list -- time-nuts@lists.febo.com
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>>> _______________________________________________
>>> time-nuts mailing list -- time-nuts@lists.febo.com
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>> _______________________________________________
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> _______________________________________________
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BK
Bob kb8tq
Sat, Sep 3, 2022 5:14 AM
Hi
If you spend some time shopping, 10811’s come up from time to time
for around $50 or so ( delivered ) on eBay. At that price, buying four or
five simply to have a few spares is probably a good idea.
Bob
On Sep 2, 2022, at 12:45 AM, Mervyn Thomas via time-nuts time-nuts@lists.febo.com wrote:
Bob,
I'm with you on that and although I have 2 10811's I would be loathe to tear one apart - certainly as a last resort only and for information sake rather than being able to fix it.
Merv
On 2/09/2022 4:55 am, Bob kb8tq via time-nuts wrote:
Hi
The version you have simply has a “box” around a fairly normal
10811 OCXO. Tearing it apart is possible. It isn’t a whole lot of fun
though.
I still believe that the GPSDO board should put out +/- voltages
and not just a negative voltage. Positive tune voltages are pretty
common. Bipolar tune is unusual but not unheard of. Negative
only tune is very rare. Since the board is already out in the open,
working on it should be easier than ripping open the OCXO.
Bob
On Aug 31, 2022, at 11:21 PM, Mervyn Thomas via time-nuts time-nuts@lists.febo.com wrote:
Hi Bob,
I need to find a schematic to download for my particular version of the HP oscillator
Merv
On 31/08/2022 2:59 am, Bob kb8tq via time-nuts wrote:
Hi
If you check the 10811 schematic, the varicap is biased at roughly +6.8V internally.
The other side of the diode is what the EFC is driving. This gives them the +/- 5V
range they specify on the 10811 data sheet.
Bob
On Aug 30, 2022, at 5:39 AM, paul swed via time-nuts time-nuts@lists.febo.com wrote:
Pretty clever approach to establishing an offset. But doesn't it matter how
the vari-cap is hooked up in the oscillator circuit? If the veri-cap needs
a negative voltage to work that may indicate the cathode is at ground and
the positive voltage would forward bias the vari-cap. Just thinking about
the possible impact.
Though the cost of experimenting is $0. No harm.
Regards
Paul
WB8TSL
On Tue, Aug 30, 2022 at 1:22 AM Mervyn Thomas via time-nuts <
time-nuts@lists.febo.com> wrote:
Stephen,
An idea I may try -thanks for your response. The current involved in
the EFC line to the oscillator is extremely small-button cells would
last years.
Merv
On 29/08/2022 8:42 pm, Stephen C. Menasian via time-nuts wrote:
Merv,
If I understand your problem, the 10811's VCO control input voltage has
drifted above the output range of the GPSD driver board. If the VCO
control terminal current is low enough, you might be able to quickly
this problem by putting 1 or 2 Lithium Ion Coin cells in series with the
control lead. If only a few microamperes are involved, this solutin might
last several years.
Stephen Menasian
On Mon, 29 Aug 2022 15:56:52 +0800
Mervyn Thomas via time-nuts time-nuts@lists.febo.com wrote:
Hi Bill,
Unfortunately the 2 HP 10811's I have have no way to poke anything thru
the can to adjust a capacitor. They are completely enclosed in an
aluminium can with 2 power leads coming out with 6 pin female
connectors on the end which go to the power board as used in the HP
Z3801 GPSDO and 2 thin coax cables with SMB connectors - one marked as
10 MHz and the other as EFC. I may have to replace mine with the model
that has the tuning capacitor.
Thanks for your response.
73 Merv
On 29/08/2022 12:45 pm, Bill Beam via time-nuts wrote:
I also run a Brooks Shera/HP 10811. Still going after many years.
You must live with the limited steering voltage.
The solution is to adjust the HP 10811 tuning capacitor to get it
back near a frequency that the EFC can handle.
I have had to do this more than once. Also if replacing the
oscillator its tuning capacitor may need adjustment.
On Mon, 29 Aug 2022 11:25:26 +0800, Mervyn Thomas via time-nuts wrote:
Hi All,
I'm new to time nuts but here goes.
I built a GPS disciplined- 10MHz osc about 15 + years ago.- It
uses an HP 10811 D/Oven Oscillator and the Brooks Shera PCB and
software V402N.- The physical construction article was per James
Miller G3RUH. This unit has worked flawlessly for all these years
but now is unable to hold the freq to precisely 10MHz - it is
constantly .29 to.60 Hz high.- The DAC output which controls the EFC
into the osc outputs a negative only adjustable voltage between -3v
down to 0V and is settable by varying a 10K potentiometer.- The
Osc. now needs abouit +0.46V to bring it down to 10MHz but the DAC
does not seem able to output a positive voltage.- The DAC is an
AD1861 (obsolete) and has a +5V applied to pin 16 and a -5V applied
to pins 1 and 8. My first reaction was the HP osc. had reached the
end of it's life but the datasheet states the EFC control voltage
can be between a plus 5V and a minus 5V which varies the freq by 1Hz
so it seems it is just over half way through it's life.
I feel the Brooks s/ware would have provided some method to ensure
the DAC output could be adjusted to swing the full full 5V or at
least 3V?- I have the source code but I'm no programmer so would
appreciate any help someone can provide please.
73 de Merv- VK6BMT
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
Hi
If you spend some time shopping, 10811’s come up from time to time
for around $50 or so ( delivered ) on eBay. At that price, buying four or
five simply to have a few spares is probably a good idea.
Bob
> On Sep 2, 2022, at 12:45 AM, Mervyn Thomas via time-nuts <time-nuts@lists.febo.com> wrote:
>
> Bob,
>
> I'm with you on that and although I have 2 10811's I would be loathe to tear one apart - certainly as a last resort only and for information sake rather than being able to fix it.
>
> Merv
>
> On 2/09/2022 4:55 am, Bob kb8tq via time-nuts wrote:
>> Hi
>>
>> The version you have simply has a “box” around a fairly normal
>> 10811 OCXO. Tearing it apart is possible. It isn’t a whole lot of fun
>> though.
>>
>> I still believe that the GPSDO board should put out +/- voltages
>> and not just a negative voltage. Positive tune voltages are pretty
>> common. Bipolar tune is unusual but not unheard of. Negative
>> only tune is *very* rare. Since the board is already out in the open,
>> working on it should be easier than ripping open the OCXO.
>>
>> Bob
>>
>>> On Aug 31, 2022, at 11:21 PM, Mervyn Thomas via time-nuts <time-nuts@lists.febo.com> wrote:
>>>
>>> Hi Bob,
>>>
>>> I need to find a schematic to download for my particular version of the HP oscillator
>>>
>>> Merv
>>>
>>> On 31/08/2022 2:59 am, Bob kb8tq via time-nuts wrote:
>>>> Hi
>>>>
>>>> If you check the 10811 schematic, the varicap is biased at roughly +6.8V internally.
>>>> The other side of the diode is what the EFC is driving. This gives them the +/- 5V
>>>> range they specify on the 10811 data sheet.
>>>>
>>>> Bob
>>>>
>>>>> On Aug 30, 2022, at 5:39 AM, paul swed via time-nuts <time-nuts@lists.febo.com> wrote:
>>>>>
>>>>> Pretty clever approach to establishing an offset. But doesn't it matter how
>>>>> the vari-cap is hooked up in the oscillator circuit? If the veri-cap needs
>>>>> a negative voltage to work that may indicate the cathode is at ground and
>>>>> the positive voltage would forward bias the vari-cap. Just thinking about
>>>>> the possible impact.
>>>>> Though the cost of experimenting is $0. No harm.
>>>>> Regards
>>>>> Paul
>>>>> WB8TSL
>>>>>
>>>>> On Tue, Aug 30, 2022 at 1:22 AM Mervyn Thomas via time-nuts <
>>>>> time-nuts@lists.febo.com> wrote:
>>>>>
>>>>>> Stephen,
>>>>>>
>>>>>> An idea I may try -thanks for your response. The current involved in
>>>>>> the EFC line to the oscillator is extremely small-button cells would
>>>>>> last years.
>>>>>>
>>>>>> Merv
>>>>>>
>>>>>> On 29/08/2022 8:42 pm, Stephen C. Menasian via time-nuts wrote:
>>>>>>> Merv,
>>>>>>>
>>>>>>> If I understand your problem, the 10811's VCO control input voltage has
>>>>>>> drifted above the output range of the GPSD driver board. If the VCO
>>>>>>> control terminal current is low enough, you might be able to quickly
>>>>>> solve
>>>>>>> this problem by putting 1 or 2 Lithium Ion Coin cells in series with the
>>>>>>> control lead. If only a few microamperes are involved, this solutin might
>>>>>>> last several years.
>>>>>>>
>>>>>>> Stephen Menasian
>>>>>>>
>>>>>>> On Mon, 29 Aug 2022 15:56:52 +0800
>>>>>>> Mervyn Thomas via time-nuts <time-nuts@lists.febo.com> wrote:
>>>>>>>
>>>>>>>> Hi Bill,
>>>>>>>>
>>>>>>>> Unfortunately the 2 HP 10811's I have have no way to poke anything thru
>>>>>>>> the can to adjust a capacitor. They are completely enclosed in an
>>>>>>>> aluminium can with 2 power leads coming out with 6 pin female
>>>>>>>> connectors on the end which go to the power board as used in the HP
>>>>>>>> Z3801 GPSDO and 2 thin coax cables with SMB connectors - one marked as
>>>>>>>> 10 MHz and the other as EFC. I may have to replace mine with the model
>>>>>>>> that has the tuning capacitor.
>>>>>>>>
>>>>>>>> Thanks for your response.
>>>>>>>>
>>>>>>>> 73 Merv
>>>>>>>>
>>>>>>>> On 29/08/2022 12:45 pm, Bill Beam via time-nuts wrote:
>>>>>>>>> I also run a Brooks Shera/HP 10811. Still going after many years.
>>>>>>>>> You must live with the limited steering voltage.
>>>>>>>>> The solution is to adjust the HP 10811 tuning capacitor to get it
>>>>>>>>> back near a frequency that the EFC can handle.
>>>>>>>>> I have had to do this more than once. Also if replacing the
>>>>>>>>> oscillator its tuning capacitor may need adjustment.
>>>>>>>>>
>>>>>>>>> On Mon, 29 Aug 2022 11:25:26 +0800, Mervyn Thomas via time-nuts wrote:
>>>>>>>>>
>>>>>>>>>> Hi All,
>>>>>>>>>> I'm new to time nuts but here goes.
>>>>>>>>>> I built a GPS disciplined- 10MHz osc about 15 + years ago.- It
>>>>>>>>>> uses an HP 10811 D/Oven Oscillator and the Brooks Shera PCB and
>>>>>>>>>> software V402N.- The physical construction article was per James
>>>>>>>>>> Miller G3RUH. This unit has worked flawlessly for all these years
>>>>>>>>>> but now is unable to hold the freq to precisely 10MHz - it is
>>>>>>>>>> constantly .29 to.60 Hz high.- The DAC output which controls the EFC
>>>>>>>>>> into the osc outputs a negative only adjustable voltage between -3v
>>>>>>>>>> down to 0V and is settable by varying a 10K potentiometer.- The
>>>>>>>>>> Osc. now needs abouit +0.46V to bring it down to 10MHz but the DAC
>>>>>>>>>> does not seem able to output a positive voltage.- The DAC is an
>>>>>>>>>> AD1861 (obsolete) and has a +5V applied to pin 16 and a -5V applied
>>>>>>>>>> to pins 1 and 8. My first reaction was the HP osc. had reached the
>>>>>>>>>> end of it's life but the datasheet states the EFC control voltage
>>>>>>>>>> can be between a plus 5V and a minus 5V which varies the freq by 1Hz
>>>>>>>>>> so it seems it is just over half way through it's life.
>>>>>>>>>> I feel the Brooks s/ware would have provided some method to ensure
>>>>>>>>>> the DAC output could be adjusted to swing the full full 5V or at
>>>>>>>>>> least 3V?- I have the source code but I'm no programmer so would
>>>>>>>>>> appreciate any help someone can provide please.
>>>>>>>>>> 73 de Merv- VK6BMT
>>>>>>>>>> _______________________________________________
>>>>>>>>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>>>>>>>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>>>>>>>>> Bill Beam
>>>>>>>>> NL7F
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> _______________________________________________
>>>>>>>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>>>>>>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>>>>>>>> _______________________________________________
>>>>>>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>>>>>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>>>>>>> _______________________________________________
>>>>>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>>>>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>>>>>> _______________________________________________
>>>>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>>>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>>>>> _______________________________________________
>>>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>>>> _______________________________________________
>>>> time-nuts mailing list -- time-nuts@lists.febo.com
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>>> _______________________________________________
>>> time-nuts mailing list -- time-nuts@lists.febo.com
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>> _______________________________________________
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